This invention relates to a coating composition and in particular to a primer composition for automobile and truck bodies that has excellent chip resistance.
Automotive and truck manufacturers have done a substantial amount of research on improving the corrosion and chip resistance properties of the painted exterior sheet metal parts of automobiles and trucks. Typical chip resistant primer compositions are shown in Kordomenos et al U.S. Pat. No. 4,708,995 issued Nov. 24, 1987, Kordomenos et al U.S. Pat. Nos. 4,698,399, 4,698,398, 4,698,402 and 4,698,400 each issued Oct. 6, 1987; Kordomenos et al U.S. Pat. Nos. 4,699,957, 4,699,958 and 4,699,959 each issued Oct. 13, 1987 and Kordomenos et al U.S. Pat. No. 4,701,501 issued Oct. 20, 1987. Additional requirements have been placed on primer compositions. The compositions are to cure at lower bake temperatures than typical prior art compositions to save on energy costs and are to achieve superior chip resistance with lower film thickness in comparison to prior art compositions.